The present invention generally relates to telecommunications and more specifically to techniques for asynchronous compensation methods for communication of secure information over packet networks.
For certain applications it is necessary to be able to establish secure communications between multiple terminals. For example, the U.S. government's secure terminal unit-III (STU-III), NATO's version STU-IIb, and future narrow band digital terminal (FNBDT) are examples of such systems. In a standard network connection, two terminals are connected together across a telephone network. Typically, the telephone network is digital and converts the analog transmissions from a terminal to a digital stream. Once a connection is established between the two terminals, the call switches from a regular voice call to a modem (modulator-demodulator) call. The encrypted voice communications are sent over the modem call.
Typically, the two terminals negotiate with each other to establish a connection. This negotiation involves sending modem tones across the network between the terminals. This process may take a long time depending on how long it takes the modem tone to traverse the network. This method includes many disadvantages. For example, the time it takes two terminals to establish a connection may be long.
As disclosed in co-pending U.S. application Ser. No. 11/053,067, entitled “NON-RELAY INITIALIZATION FOR MODEMS”, filed concurrently, terminals may negotiate in parallel with communication gateways in a non-relay mode. Accordingly, a first terminal may finish it's negotiation with a first gateway before a second terminal finishes its negotiation with a second gateway. After the first terminal finishes its negotiation, it may start sending data to the second terminal. This data is stored in a queue at the second gateway until the second terminal and second gateway finish their negotiation. This may result in a large one-way backup of data. Thus, a large one way delay occurs because data in the queue is sent before new data. Thus, if a conversation is taking place and the second terminal sends data and a response to the data is sent by the first terminal, the response may not be sent to the second terminal right away because of the data backup in the queue. Thus, a conversation may not be synchronized because of the data backup.